Jerguson · Level Switches
Jerguson top mount displacer and float operated magnetic level switches
Tri-Magnet level switches mounted on top of the vessel, Series JD displacer operated with switch points many feet below the flange for multi-point alarm and pump control, or float operated; 3" to 6" flanges Class 150 to 600 or 2-1/2" and 3" MNPT, SureTest option.
Top mount switches are installed on a nozzle on the roof of the vessel. With the displacer version the switch or control points can sit many feet below the mounting flange, which suits pump control with wide differentials and multi-point alarms from a single connection.
The displacer elements hang on a stainless steel cable from a spring. As the liquid covers or uncovers a displacer, its apparent weight changes and the spring moves a rod and magnet up or down inside the pressure tube, which snaps the Tri-Magnet switch over without any mechanical link through the pressure boundary. The displacers can be repositioned on the cable in the field. Because of the spring, the displacer version is limited to 400 °F.
The SureTest option adds a manual check: the operator moves a strong rare earth magnet along the outside of the tube to simulate a high level and verify that the switch trips, then releases the handle and springs return it. SureTest Rooftop brings this check to the tank roof.
Selection data we need
Switch points and their depth below the flange, single or dual switch and differential, medium and specific gravity, design pressure and temperature, mounting connection, switch mechanism and contacts, area classification and whether SureTest is required.
Applications
- Pump control with wide differentials
- Multi-point high and low alarms on tanks and sumps
- Tank overfill protection with in-place testing (SureTest, see API 2350)
